1 The Eutrophication Problem in Temperate
Lakes: Practical Aspects and Theoretical
Ramifications
Scientists are perennially aware that it is best
not thrust theory until it is confirmed by
evidence. It is equally true ... that it is best not
to put too much faith in facts until they have
been confirmed by theory.
R. MacArthur
The effects of anthropogenic eutrophication caused by using lakes and
rivers as recipients for municipal, agricultural and industrial wastes are
often found to be in conflict with commercial and recreational uses of the
same localities. If we take Norway as an example, a recent survey of 355
Norwegian lakes (Faafeng et al. 1990) concluded that only 7% of the investigated lakes could be unambiguously classified as eutrophic, of which the
majority has probably been eutrophicated by human activity. As this
survey was deliberately biased toward lakes located in urban areas, we cannot multiply this figure with the number oflakes in Norway (approximately
400 000 lakes larger than 0.5 ha), to obtain to the total number of eutrophicated lakes. It is not even certain that an unbiased estimate of the number
of eutrophicated lakes would be of much value, as the recreational and
commercial value to the general public would be expected to be very much
higher for lakes located in populated areas. While eutrophication appears
to be a problem only on a local scale in some countries, it is still recognized
as a major environmental problem in more densely populated areas of
central Europe and north America.
Even though wastewater treatment technology is continually improving,
the costs of water-treatment processes are usually steeply increasing when
the nutrient removal efficiency is approaching 100%. Despite the large
investments made by developed countries in wastewater treatment,
eutrophication problems will probably nevertheless be something we will
have to live with for a long time yet. It might even be argued that complete
removal of anthropogenic nutrients is not always a desirable goal; some
mild level of nutrient enrichment can, in many instances, be quite beneficial by increasing secondary production, and thereby transforming human
wastes to valuable food resources.
Lakes: Practical Aspects and Theoretical
Ramifications
Scientists are perennially aware that it is best
not thrust theory until it is confirmed by
evidence. It is equally true ... that it is best not
to put too much faith in facts until they have
been confirmed by theory.
R. MacArthur
The effects of anthropogenic eutrophication caused by using lakes and
rivers as recipients for municipal, agricultural and industrial wastes are
often found to be in conflict with commercial and recreational uses of the
same localities. If we take Norway as an example, a recent survey of 355
Norwegian lakes (Faafeng et al. 1990) concluded that only 7% of the investigated lakes could be unambiguously classified as eutrophic, of which the
majority has probably been eutrophicated by human activity. As this
survey was deliberately biased toward lakes located in urban areas, we cannot multiply this figure with the number oflakes in Norway (approximately
400 000 lakes larger than 0.5 ha), to obtain to the total number of eutrophicated lakes. It is not even certain that an unbiased estimate of the number
of eutrophicated lakes would be of much value, as the recreational and
commercial value to the general public would be expected to be very much
higher for lakes located in populated areas. While eutrophication appears
to be a problem only on a local scale in some countries, it is still recognized
as a major environmental problem in more densely populated areas of
central Europe and north America.
Even though wastewater treatment technology is continually improving,
the costs of water-treatment processes are usually steeply increasing when
the nutrient removal efficiency is approaching 100%. Despite the large
investments made by developed countries in wastewater treatment,
eutrophication problems will probably nevertheless be something we will
have to live with for a long time yet. It might even be argued that complete
removal of anthropogenic nutrients is not always a desirable goal; some
mild level of nutrient enrichment can, in many instances, be quite beneficial by increasing secondary production, and thereby transforming human
wastes to valuable food resources.